Retail sales on the UK high street suffered their sharpest monthly drop in 18 months in January as the snow and icy weather deterred shoppers.

The Office for National Statistics (ONS) said today that sales volumes dropped 1.8% during January. This is more than three times what analysts had expected and the biggest monthly fall since June 2008. On the year, sales were up 0.9%.

The figures heightened fears of a "double-dip" recession among economists. Jonathan Loynes, chief European economist at consultants Capital Economics, said: "January's retail sales figures round off a pretty awful week for news on the UK economy. As well as high inflation, rising unemployment and record public borrowing, we can now add a sharp drop in high street spending.

"Of course, we knew the January sales figures would be bad after the VAT rise and bad weather. But the drop is even worse than the retail surveys had suggested … At the very least, these numbers provide a very weak platform for sales in the first quarter of this year and therefore raise the chances that the economy may succumb to a double dip."

The ONS said that the unusually heavy snow at the start of the month pushed down sales of household goods by 13.4% in January – the biggest drop since January 1988. Fuel sales fell by 11.1% on the month as motorists stayed at home unable to get out in the snow.

Sterling hit a nine-month low against the dollar after the data. The pound fell about half a US cent to $1.5345 – its weakest since May 2009.